Free vane magnetic circuit



May 26, 1970 P. E. UGON FREE VANE MAGNETIC CIRCUIT Filed Nov. 5, 1967 3 Sheets-Sheet 1 May 26, 1970 P. E. uGoN 3,514,728

FREE VANE MAGNETIC CIRCUIT Filed Nov. 3. 1967 3 Sheets-Sheet 2 A ORNEYS May 26, 1970 y P. E. uGoN 3,514,728

FREE VANE MAGNETIC CIRCUIT Filed NOV 5, 1967 3 SheeS-Sheet 5 44 N" ,I S

INVENTOR P/'ef Uso/V ORNEYS United States Patent Oihce 3,514,728 Patented May 26, 1970 3,514,728 FREE VANE MAGNETIC CIRCUIT Pierre Eugene Ugon, 21 Rue Claude de Bussy, 78 St. Germain-en-Laye, France Filed Nov. 3, 1967, Ser. No. 680,550 Claims priority, application France, Nov. 4, 1966, 82,556; Sept. 27, 1967, 122,395 Int. Cl. H01h 9/00 U.S. Cl. 335--179 12 Claims ABSTRACT OF THE DISCLOSURE An electromagnetic switching apparatus including electromagnetic means defining an armature housing cavity and having at least two spaced stops each formed of electrically conductive material. Means are also included providing a low reluctance path outside the cavity from one stop to the other and one section of the path is electrically nonconductive to electrically isolate the stops. A coil is provided to vary the magnetic eld conditions within the cavity in accordance with an operating signal applied thereto. Each stop is electrically connected to a utilization circuit. An armature of magnetic material is provided within the cavity and either the armature or the electromagnetic means includes a permanent magnet. The armature is freely movable and oating within the cavity to operatively engage both said stops and disengage and move away from at least one of the stops in response to the magnetic iield conditions developed by the control signal. The armature has an outer layer of electrically conductive material to contact and electrically connect the stops when the armature engages therewith. Either one or both of the stop material or the armature outer layer material has high reluctance to provide a high reluctance but electrically conductive material extending from the magnetic part of the armature to the low reluctance path when the armature engages said stops.

BACKGROUND OF THE INVENTION The present invention relates to free vane electromagnetic circuits such as relays or the like and more particularly to such devices wherein the poles of the magnetic circuit are electrically isolated from the rest of the magnetic circuit which closes the magnetic path between the poles and wherein a nonmagnetic but electrically conductive material extends from the magnetic parts of the armature to each respective (effective) pole when the armature is in the magnetically closed position.

Free vane electromagnetic relays and the like have been known for several decades. By virtue of the elimination of armature pivots, bearings, and other like supports, these free vane devices, in principle, provide switching arrangements in less volumetric space than is required for conventional relays of the non free vane type. However, known free vane relays of the type described have not been free of problems -which have limited the degree of miniaturization obtainable with conventional designs. For example, prior free vane devices include at least a pair of electrical connections or stops arranged within the armature cavity. These stops are physically spaced from the ends of the pole shoes primarily to prevent the armature from contacting the pole shoes and thereby creating magnetic hysteresis problems and to assure electrical isolation between the associated stops. The space between each stop and the respective pole shoe is conventionally lled with air or insulating material such as paper or the like.

In view of the growing present demands for miniaturization of these devices, there s an important need in the art to miniaturize these devices even further than have been possible with conventional designs. The present invention provides a new and improved arrangement which affords greater miniaturization than heretofore possible. Brieily stated, the invention for the lirst time provides a device of the type described wherein the electrically conductive contacts or stops are attached directly to the poles or pole pieces thus permitting a reduction in the volume necessary for the armature cavity. At least part of the magnetic circuit outside the cavity includes an electrical nonconducting section to electrically isolate one stop from the other. The armature includes a body of magnetic material and at least an outer layer of electrically conductive material to make electrical connection between stops when the armature engages therewith. In order to prevent problems due to magnetic hysteresis (such as armature sticking), either the stop material or the armature conductive layer or both is formed of nonmagnetic material so that when the armature is closed, a nonmagnetic but electrically conductive safety gap extends from the magnetic part of the armature to the pole or pole pieces.

It is therefore an object of the invention to provide a free vane electromagnetic relay or the like which obtains the advantages and avoids the problems outlined above.

Other and further objects of the invention will become apparent with the following detailed description of the embodiments when taken in view of the appended drawings in which like characters refer to like structure and in which:

FIG. 1 is a diagrammatic illustration of a vertical section through one embodiment of the invention.

FIG. 2 is a horizontal section taken along line 2 2 of y FIG. 1.

FIGS. 3, 4 and 5 are views similar to FIG. 1 illustrating further embodiments of the invention.

FIG. 6 is a partial exploded view of a modification of certain parts of the embodiments of FIG. 5.

FIGS. 7 and 8 are views similar to FIG. l illustrating additional embodiments ofthe invention.

With reference to FIG. 1, a switching device lgenerally indicated as 10 according to the invention includes a pair of spaced electrical nonrnagnetic insulators 12 and 14 positioned within a suitable housing or can 16. The electromagnetic apparatus generally indicated as 18 is supported within can 16 between insulators 12 and 14, and includes a pair of diametrically positioned permanent magnets 20 and 22 which in this example are formed of ferrite material which, as is commonly known, is electrically nonconductive. Pairs of electrically conductive magnetic pole pieces 2-4, 26 and 28, 30 extend from respective poles of magnets 20 and 22 toward each other and terminate to provide an armature housing cavity 32. A spacer 17 of suitable material separates the can 16 from the electromechanical assembly 18, for example, spacer 17 may be an air space or tlled with a potting material. Each pole shoe facing cavity 32 is coated with an electrically conductive, nonmagnetic material 34 which acts as the electrical contact or stop for the armature as described below. Stops 34 are preferably formed of silver; however, metals such as nickel may be suitable but less etlicient than silver. It can be seen that each stop 34 is electrically isolated from its associated stop through the magnetic path defined outside the cavity by virtue of the electrically nonconductive material forming magnets 20 and 22. Moreover, since each magnet electrically isolates the pole pieces in this low reluctance path, electrical connections to the stops 34 are preferably made through leads 36, 38, 40, 42 which are connected to the respective pole piece as shown by suitable solder connection or the like. The operating coil 44 is wound about cavity 32 generally as shown andthe operating signal is applied thereto through lead connections 46 and 48.

The armature 50 floats in cavity 32 and is dimensoned to simultaneously engage associated pairs of stops 34 depending upon the magnetic field conditions generated by coil 44. Armature 50 is formed of a suitable magnetic material such as soft iron and has outer layers of electrically conductive, nonmagnetic material 52 such as silver or the like.

In operation, it can be seen that -when armature 50 is moved by coil 44 to engage one pair of stops such as shown in FIG. l, the gap between the magnetic part of armature 50 and each magnetic pole piece 24 and 26 is completely filled with electrically conducting, nonmagnetic material, i.e., the material forming each stop 34 and the respective outer armature layer 52. In this way, the arrangement as disclosed avoids magnetic hysteresis problems and effectively eliminates non current carrying spaces by filling the safety gap between armature 50 and the pole pieces when closed with electrically conductivenonmagnetic contact material.

It will be appreciated that it may be possible to eliminate the outer nonmagnetic layers 52 of armature 50 and still practice the invention. In this case, electrical connection between stops 34 is made through the armature soft iron body 50 while the magnetic safety gap is provided by the electrically conductive nonmagnetic material of stops 34, which would have a suitable thickness to give the desired results. Similarly, stops 34 can be formed by the pole shoes so that the nonmagnetic, conductive layers 52 of armature 50 provide the aforementioned results.

A second embodiment of the invention is illustrated in FIG. 3 wherein ferrite magnets are replaced by metallic magnets 54 and 56 which, of course, are electrically conductive. In this embodiment, associated pairs of stops 34 are electrically isolated by thin insulating sheets 58 covering the entire surface of the respective poles thereby separating the pole and pole piece. Sheets 58 may be applied at one or both poles of each magnet 54 and 56. The thickness of sheet 58 should be suitably small so as to add only negligible reluctance to the magnetic circuit.

The embodiment shown in FIGS. l, 2 and 3 have been built in accordance with the invention and fitted in a can 16 having dimensions no bigger than 8 mm. in diameter and a height of 6 mm. Smaller dimensions are anticipated.

The embodiment of FIG. 4 provides an arrangement of fewer parts than the aforementioned embodiments of FIGS. 1 and 2. Specifically, ferrite magnets 20 and 22 are located contiguous to the armature housing cavity 32 and contacts 34 are attached directly to the magnet poles. Magnets 20 and 22 being formed of ferrite material or the like provide electrical isolation between associated pairs of stops 34. Coil 44 is Wound about the entire cavity and magnet assembly as shown. The thickness of stops 34 are sufficient to permit attachment of leads 60, 62, 64 and 66. Furthermore, since magnets 20 and 22 are nonconducting, efficient production methods can be used to extend these leads to stops 34 by coating the leads directly on magnets 20 and 22. Electrical deposition of the lead and contact material may be obtained by any suitable means such as cathole deposition or electrolysis deposition now commonly used in the printed circuit board art.

Normally, problems would result from the close positioning of the magnet and armature as provided in the embodiment of FIG. 4. However, such close positioning is efficiently achieved herein by virtue of the large difference in permeability between the ferrite magnets and the iron armature body. Specifically, the iron permeability is several thousand times greater than that of each ferrite magnet. Therefore, the magnetic characteristics of armature 50 is modulated to a much greater extent than are magnets 20 and 22 in response to changing field conditions induced by coil 44. Furthermore, if we compare this design to the embodiments of FIGS. 1 and 3, the mutual proximity 4 of leads 60, 62 and 64, 66 reduces the induction therein in response to excitation of the operating coil 44.

The embodiment of FIG. 5 provides an arrangement wherein the magnetic circuit also serves as part of the electric circuit. This embodiment includes a housing or can 68 which is formed of magnetic material. A pair of ferrite magnets are arranged on opposite sides and near one end of cavity 32 and are oriented with their poles in mutual horizontal alignment. The poles of these magnets furthest from cavity 32 are connected to opposite sides of can 68 so that the latter serves as a pole piece for each magnet. Operating coil 44 is wound about cavity 32 generally as shown. A pair of depending abutrnents or stops 72 form a groove 74 which extends into the top end of cavity 32. Stops 72 are preferably made of silver or other nonmagnetic-electrically conductive material.

The pole of each magnet 20 and 22 facing cavity 32 is inclined and coated with electrically conductive nonmagnetic material such as silver to form stops 34. Armature 50 floats in cavity 32 and includes electrically conductive nonmagnetic outer layer 52 which covers both side faces and defines a rounded top 76 for the soft iron body part of armature 50.

In operation, stops 34 are electrically isolated from each other since they only contact the ferrite material. When armature 50 is moved under the influence of coil 44 to close one of the magnetic circuits such as the one illustrated, the bottom of armature 50 is pulled flush against the inclined face of the respective stop 34. The motion of armature 50 is generally arcuate while the rounded top 76 remains in electrical contact with stops or electrical contacts 72. In this way, electrical connection is made through stop 34 associated with magnet 20, layer 52, stop 72, and can 68 to the electrical lead 78 electrically connected thereto. Again, the magnetic part of armature 50 when closed with one of the magnets is separated from the magnet pole only by electrically conductive, nonmagnetic material.

A modification of the contact arrangement of the embodiment of FIG. 5 is illustrated in FIG. 6. Specifically, pole pieces formed of soft iron 80 and 82 are secured between the ferrite magnetic poles and the respective electrical stop 34. Since pole pieces 80 and 82 are electrically conductive, the electrical leads to the utilization circuit are taken from these pole pieces there-by simplifying fabrication.

A further modification (not shown) comprises ferrite magnets 20 and 22 being replaced with electrically conductive ones but each with its outer pole separated from can 68 by a thin electrical insulator. This modification employs an arrangement technique similar to that disclosed herein in connection with FIG. 3.

The embodiments as disclosed above may have a pair of permanent magnets poled in opposite directions so as to provide a bistable working device. Alternatively, if the magnets are poled in the same sense, i.e., north-tonorth, south-to-south, the device operates as a flip-op which changes conditions for each pulse of the same polarity. Thereby, if a series of pulses of the same polarity are applied to the operating coil the armature moves to engage the opposite pair of contacts for each pulse applied notwithstanding the pulse being of the same polarity. Furthermore, in the above embodiments, if one magnet is replaced by a soft fer-rite formed of a permeable nonmagnetic material, and which is nonpolarized, the device operates in a monostable mode.

Relay devices including several sections of the embodiments depicted in FIGS. l, 3 and 5 are `also possible. In this case, the outer can is elongated and a plurality of stages of one of the embodiments are spaced one next to the other throughout the length of the can. In this arrangement, only two opposite magnets extending substantially the length of the can would be needed to polarize magnetically the poles of all individual stages at the same time. The individual function of each of these devices or stages will not effect or is not effected by other stages within the can and each stage effectively operates its own armature. Also possible is such an elongated device having a plurality of stages with a single operating coil extending through all stages. In this case, a single operating current applied to the coil eiects the positioning of all armatures of all stages. Further variation includes a can having, for example, five stages with, for example, two operating coils, one coil driving three of the stages and the other coil acting on the other two stages. Twovdiierent power supplies are provided each controlling opposite ones of the operating coils.

Turning now to the embodiment of FIG. 7, there is illustrated an electromagnetic relay in which the free vane armature comprises a ferrite or soft iron permanent magnet 84 having opposite faces coated with layers of nonmagnetic electrically conductive material 52 such as silver or the like. The pole pieces 86, y88, 90 and 92I are spaced to form cavity 32 within which armature 52 floats. Electrical contacts or stops 34 are attached to the respective pole piece ends nearest cavity 32 and aligned with the poles of magnet 84. The pole pieces and consequently the stops 34 are electrically insulated from each other and electrical lead connections are made to these pole pieces in the manner described. Coil 44 is wound about the cavity 32 between the pole pieces so as to generate electromagnetic fields to magnetiz pole 86 opposite from pole 88 and pole 90 opposite from pole 92. The magnetic circuit for poles 86 and 88 and poles 90 and 92 is completed through the associated parts of can 94 which is formed of magnetic material such as soft iron or the like. If desired, the magnetic circuit can be completed through a magnetic soft iron part (not shown) connecting the outer ends of the pole pieces and which part is separate from the can 94. A complementary magnetic piece 96 is positioned outside cavity 32 between pole pieces 86 and 90 so as to move magnet `84 in contact with stops 34 on pole pieces 86 and 90 to establish an initial position for the magnet when the actuating current is removed from coil 44. If desired, part 96 can have any suitable position and in some instances its function may be provided by the bottom 98 of the can itself. Suitable insulating material may be provided to support the assembly parts within can 94 where necessary.

In operation, when no current is applied to coil 44, the armature experiences a force in the direction of part 96 by virtue of the lower reluctance path established on that side of cavity 32 than on the other. Armature 84 moves to close the contacts 34 of pole pieces 86 and 90. When energizing current is applied to coil 44, the induced magnetic field in the pole pieces repels one4 end of armature -84 so that it -moves away to contact the stop on one of the pole pieces 88 and 92. For example, armature 84 may be actuated to connect the stops on pole pieces 86 and 92 by a signal to coil 44 of one polarity and to connect the stops on pole pieces 88y and 90 by a signal of opposide polarity. Whenever the coil signal is removed, armature 84 returns to its initial position engaging pieces 86 and 90'.

In the embodiment of FIG. 8, with can 94 formed of magnetic material, it is possible to eliminate the pole pieces as compared to the embodiment of FIG. 7. In FIG. 8, the magnetic armature is still effected by the electromagnetic fields developed by coil 44 which are concentrated by the magnetic can (such as soft iron) 94. The electric contacts or stops 34 are supported at the ends of leads G-106 having suitable dimensions for strength purposes. Of course, electrical insulation r'nay be applied within can 94 where necessary or desirable to secure the positions of stops 34. Armature movement and initial positioning is the same as described for the embodiment of FIG. 7.

Thus, there has been described a new and improved electromagnetic relay which achieves results not heretofore possible in the art. -It will be understood that the vario-us embodiments hereof are only disclosed by Way of examples and other and further modifications of the invention may be made without avoiding the spirit or scope thereof. For example, the invention may be used in other than free vane devices such as reed switch relays and the like. In that case at least one of the reeds is coated with the nonmagnetic, electrically conductive layer so that when the reeds engage, the layer material thickness extends from one magnetic reed part to the other magnetic reed part.

What is claimed is:

1. An electromagnetic switching apparatus comprising electromagnetic means defining an armature housing cavity and having at least two spaced stops each comprising electriclly conductive material, means providing a low reluctance path outside the cavity from one stop to the other and one section of the path being electrically nonconductive to electrically isolate the stops, said electromagnetic means further including a coil to vary the magnetic field conditions within the cavity in accordance with an operating signal applied thereto, a pair of electrical connections each coupled to an opposite stop and being adapted to be operatively connected to a utilization circuit, a magnetic armature, one of said electromagnetic means and said armature including a permanent magnet, said armature being freely movable and fioating within said cavity to operatively engage both said stops and disengage and move away from at least one of said stops in response to the magnetic field conditions developed by said control signal, said armature having an outer layer of electrically conductive4 material to contact and electrically connect the stops when said armature engages therewith, and at least one of said layer and said stop material being of high reluctance to provide a high reluctance but electrically conductive material extending from the magnetic part of the armature to the low reluctance path when the armature engages said stops.

2. The apparatus of claim 1 wherein said electromagnetic means comprises the permanent magnet having one pole magnetically coupled to one stop and the other pole magnetically coupled to the other stop, and wherein both said layer and said stop material have high reluctance characteristics.

3. The apparatus of claim 2 wherein the permanent magnet is spaced from said cavity and pair of stops, a pair of electrically conductive magnetic pole pieces each extending from the region near opposite poles of said magnet to opposite stops and being electrically connected thereto, each of said electrical connections being connected to the associate pole piece, and said pole pieces being electrically isolated from each other by said one section of said low reluctance path between the stops.

4. The apparatus of claim 3 wherein said one section of the low reluctance path comprises the permanent magnet which is formed of magnetic but electrically nonconductive material.

5. The apparatus of claim 3 wherein the permanent magnet is formed of electrically conductive material and said one section of the low reluctance path includes a thin electrical insulator separating one of the pole pieces from the associated magnet pole.

6. The apparatus of claim 3 wherein the electromagnetic means further comprises a'second pair of such stops arranged on the opposite side of said armature as said firstmentioned pair, a second permanent magnet spaced from the second stops, a second pair of such pole pieces extending from opposite poles of said second permanent magnet to opposite ones of said second stops and being electrically connected thereto to form a low reluctance path between said second stops outside said cavity and said electromagnetic means further including means forming one section of said last-mentioned low reluctance path which is electrically nonconductive to electrically isolate said second pole pieces, a second pair of such electrical connections each connected to opposite ones of said second pole pieces, said armature including a second electrically conductive high reluctance outer layer facing the second stops, and said coil being wound generally symmetrically about said cavity to operatively move the armature to electrically connect said first-mentioned pair of stops in response to an operative signal applied thereto, and when the armature engages said second pair of stops the second outer layer and respective second stop extend generally continuously from the magnetic part of said armature to the low reluctance path extending between said second pair of stops.

7. The apparatus of claim 2 wherein said one section of the low reluctance path is formed by the permanent magnet which is formed of magnetic but electrically nonconductive material, said stops being attached to opposite poles of said permanent magnet, and said coil is wound about both said cavity and permanent magnet.

8. The apparatus of claim 2 wherein the permanent magnet poles are aligned with one armature end and generally parallel to the direction of armature movement, said coil being wound about said cavity and parts of the armature not aligned with the magnet poles, one stop being arranged between said one end of the armature and the nearest magnet pole and the other stop positioned to contact the armature near its other end, said first stop being shaped to pivot the armature about an imaginary axis when said one end is attracted thereto and to move the other armature end in the same rotational direction to engage the other stop.

9. The apparatus of claim 8 wherein a pole piece connects the magnetic pole facing away from the armature with the other stop and said permanent magnet is formed of electrical nonconductive material.

10. The apparatus of claim 9 wherein an electrically conducting pole piece extends from the magnet pole facing the armature and said one stop, and one electrical connection is connected to said last-mentioned pole piece.

11. The apparatus of claim 1 wherein the armature comprises the permanent magnet, a pair of pole pieces each connected to opposite ones of said stops and positioned within the flux fields developed by the coil and means spaced from one side of the armature to effect movement of the armature to a predetermined initial position relative said stops whenever the coil operating signal is terminated.

12. An electromagnetic switching apparatus, comprising a can formed of magnetic material, a coil wound within said can so as to form an armature cavity therein, an armature having opposite faces coated with a layer of electrically conductive and magnetically insulating material, said armature being a permanent magnet, magnetized in a direction perpendicular to the axis of the coil, two pairs of stops formed of electrically conductive material and each stop being supported in electrical isolation from the others, each pair being arranged on opposite sides of the cavity such that the armature electrically connects the stops upon engagement therewith in response to magnetic fields developed by operating signals applied to said coil.

References Cited UNITED STATES PATENTS 1,953,929 4/1934 Droysen 335-82 2,830,152 4/1958 Tasker 335-82 2,919,323 12/1959 Drescher 335-82 2,923,792 2/1960 Fry 335-82 3,030,469 4/ 1962 Lazich 335-179 3,040,146 6/1962 Immel 335-179 BERNARD A. GILHEANY, Primary Examiner H. BROOME, Assistant Examiner 

